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Help With Understanding the ISF Engine Construction

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Old Mar 23, 2016 | 07:27 PM
  #16  
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Not to get into a "my daddy can beat up your daddy" argument...but I've built and raced late-model GM cars for the past 18 years (Camaro's and Z06's). The LSx motor is as reliable as they come. Left in purely stock (or mildly modified) form, they'll run for 180K+ miles without breathing hard. Of course stock LSx motors are about as common as Purple Unicorns. My IS-F presently shares garage space with a 515rwhp naturally aspirated LS3 powered Camaro that runs and performs flawlessly. While I won't say that GM cars don't have some short-comings...the LSx platform is definitely not one of them. Although it may be dumb and simple (like was stated in an earlier post)...sometimes, simple is better. If you want to build crazy, reliable horsepower for cheap...the LSx is your ticket. Again, this is not meant to diminish the ISF 2UR motor. It's a fine piece of engineering and excels at all that it does. I just wanted to clear up any misinformation about the reliability of GM/LSx motors.
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Old Mar 23, 2016 | 07:30 PM
  #17  
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Originally Posted by juanmedina
We don't really need this engine to rev to the moon, 6800rpm seems acceptable to me.... We seem to forget that we have a transmission that can shift in 100ms
Certainly doesn't downshift in 1/10th of a second.
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Old Mar 23, 2016 | 07:56 PM
  #18  
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Originally Posted by juanmedina
What about the new C7 Z06 that blew up with only a few miles or the ones that pull timing because of improper cooling....
What does this have to do with my car or the C6 Z06?

But since we have a hard on for C7Z issues, the engine failures occured in less than 1% of C7Zs. Additionally it is advised that the C7 Z06 gets an oil change at 500 miles (which should be standard on any new engine imo) to clear the engine of any contamination resulting from break in (I changed the oil in my new engine at 400mi and 1000mi).

Pulling timing due to improper cooling... any car is susceptible to heat soak. Forced induction cars more so. Are you referencing the test car that heat soaked during a magazine test that had suffered damage prior to the test? Several C7Z owners report minimal negative effects after 15 lap sessions with the fastest laps being later in the session.

The target for the Z06 was to have no degradation in performance being lapped by a professional with 85 degree ambient temps.

Everyone that has logged IAT1 vs. IAT2 has found the IAT2 numbers to be quite impressive, suggesting that heat soak is not an issue.

Several tuners have also discovered the factory tuning to be very conservative.

But this is the Internet. What affects one must affect all, right?
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Old Mar 24, 2016 | 02:35 AM
  #19  
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Originally Posted by SubOrbital
Certainly doesn't downshift in 1/10th of a second.
How fast is the downshift? It feels faster than what I can probably downshift a manual car
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Old Mar 24, 2016 | 02:38 AM
  #20  
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Originally Posted by RyanMcZ06
What does this have to do with my car or the C6 Z06?

But since we have a hard on for C7Z issues, the engine failures occured in less than 1% of C7Zs. Additionally it is advised that the C7 Z06 gets an oil change at 500 miles (which should be standard on any new engine imo) to clear the engine of any contamination resulting from break in (I changed the oil in my new engine at 400mi and 1000mi).

Pulling timing due to improper cooling... any car is susceptible to heat soak. Forced induction cars more so. Are you referencing the test car that heat soaked during a magazine test that had suffered damage prior to the test? Several C7Z owners report minimal negative effects after 15 lap sessions with the fastest laps being later in the session.

The target for the Z06 was to have no degradation in performance being lapped by a professional with 85 degree ambient temps.

Everyone that has logged IAT1 vs. IAT2 has found the IAT2 numbers to be quite impressive, suggesting that heat soak is not an issue.

Several tuners have also discovered the factory tuning to be very conservative.

But this is the Internet. What affects one must affect all, right?
Well I heard of C6 Z06 dropping valves just because
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Old Mar 24, 2016 | 04:49 AM
  #21  
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Originally Posted by juanmedina
Well I heard of C6 Z06 dropping valves just because
Sigh. Here we go.
It has happened. Yet several have seen thousands of track miles with no issue at all. I've heard some ISF have had water pump failures and transmission issues. I heard there was a recall due to a leaking fuel filler hose. I heard my cousins uncles best friends neighbor had an isf engine failure.

Every car has its issues and it doesn't take much to Google any car built and find some problem that someone has experienced. Doesn't mean they all experience the issue or that there is even a significant percentage having the issue. The ones who have issues are typically the loudest voices and quickly create Internet hysteria.
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Old Mar 24, 2016 | 06:54 AM
  #22  
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Originally Posted by juanmedina
How fast is the downshift? It feels faster than what I can probably downshift a manual car
Hell if I know, but I know I have enough time to think "well that wasn't lightning fast."
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Old Mar 24, 2016 | 09:43 AM
  #23  
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Originally Posted by juanmedina
Well I heard of C6 Z06 dropping valves just because
And some Lexus cars have leaking fuel filler necks , valve spring issues, transmission/tcu issues, water pump issues, and accelerator pedal problems just because.

Its not just because. There is a known cause to the problem. The LS7 valve drop issue is due to incorrect machining of the valve guide causing it to not be concentric with the valve stem. This leads to excessive friction and failure of the valve. The casting of the heads was done by Linamar.

Cars are complex machines and you will be hard pressed to find one that has been mass produced without any failures or shortcomings.
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Old Mar 24, 2016 | 09:44 AM
  #24  
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Originally Posted by SubOrbital
Hell if I know, but I know I have enough time to think "well that wasn't lightning fast."
I found a graph that shows the downshift time and it seem that the IS-F tranny downshifts quite fast about 0.185ms. IIRC a human takes 0.5ms to shift.


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Old Mar 24, 2016 | 09:52 AM
  #25  
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Originally Posted by juanmedina
How fast is the downshift? It feels faster than what I can probably downshift a manual car
I just read a link here posted by someone and I forgot who or what the link was but it was a detailed review on the ISF and they went through all facets of the ISF and I remember the downshift time was .02 sec or twice as long as the .01 upshift which is still quick and I have no issues with how long the ISF transmission upshift at
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Old Mar 24, 2016 | 10:17 AM
  #26  
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Originally Posted by RyanMcZ06
Sigh. Here we go.
It has happened. Yet several have seen thousands of track miles with no issue at all. I've heard some ISF have had water pump failures and transmission issues. I heard there was a recall due to a leaking fuel filler hose. I heard my cousins uncles best friends neighbor had an isf engine failure.

Every car has its issues and it doesn't take much to Google any car built and find some problem that someone has experienced. Doesn't mean they all experience the issue or that there is even a significant percentage having the issue. The ones who have issues are typically the loudest voices and quickly create Internet hysteria.
Originally Posted by RyanMcZ06
And some Lexus cars have leaking fuel filler necks , valve spring issues, transmission/tcu issues, water pump issues, and accelerator pedal problems just because.

Its not just because. There is a known cause to the problem. The LS7 valve drop issue is due to incorrect machining of the valve guide causing it to not be concentric with the valve stem. This leads to excessive friction and failure of the valve. The casting of the heads was done by Linamar.

Cars are complex machines and you will be hard pressed to find one that has been mass produced without any failures or shortcomings.
Sounds like you've heard BS about the IS F too. Here's what I know from someone who has owned 8 C5s and C6s all Z06s and had every single one of them bought back by Chevrolet (he now has a Hellcat and a new Viper). The C7 cooling system is inadequate. He was able to make the engine overheat in less than 6 laps at TWS. He said the C7 Z06 does not have a bigger cooling system than the standard model, so he decided not to waste any time with one, hence the Hellcat and the Viper.

This is him at TWS:


I feel sorry for his cars, but I know he is able to push them very hard.
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Old Mar 24, 2016 | 10:20 AM
  #27  
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Originally Posted by lobuxracer
Sounds like you've heard BS about the IS F too.
I feel sorry for his cars, but I know he is able to push them very hard.
I think the conclusion to the Internet pissing match is every car has problems therefore every car sucks.
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Old Mar 24, 2016 | 10:33 AM
  #28  
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Originally Posted by RyanMcZ06
I think the conclusion to the Internet pissing match is every car has problems therefore every car sucks.
I would say some failures suck more than others. Spinning a rod bearing in a bone stock factory built engine should almost never happen. Sadly, BMW have had this happen. Breaking a crankshaft because the machine failed to radius the main journals on the crank should never happen, but did happen to Mitsubishi's GT3000 VR4 in '91. Breaking valve springs and dropping valves should never happen, but it has happened innumerable times over the years to just about every manufacturer because the accountants thought they could save money with cheaper springs.

Not all cars suck. All catastrophic failures suck especially when they start to be consistently problematic.

Yes, no doubt Aisin built a whole lot of water pumps for Lexus V-8s that failed prematurely. No one here lost an engine to it, and everyone who had a pump fail either got full warranty replacement or got assistance with the cost from Lexus.

But if you really want an Internet pissing match with no discernible outcome, you should go to the RC F forum and engage with ISF001. He will vehemently deny any issues with the RC F...
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Old Mar 24, 2016 | 10:38 AM
  #29  
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Originally Posted by lobuxracer
But if you really want an Internet pissing match with no discernible outcome, you should go to the RC F forum and engage with ISF001. He will vehemently deny any issues with the RC F...
Lol. That wasn't my intent here. I just wanted correct some details a friend put in his post. Then I got drug into it. Regarding your friend with 8 buy backs... that seems excessive and would lead me to question it. If you sell a man a hammer and he returns it for another 8 times you have to ask if he's using it as intended. Lol. But you know him better than I.
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Old Mar 24, 2016 | 12:19 PM
  #30  
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^^^^ Lobuxracer last paragraph about ISF001 almost made me spit out my lunch hilarious.
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